Telephone system



Dec. 15, 1931. R TAYLOR 1,836,996

TELEPHONE SYSTEM Filed April 13.1929 8 Sheets-Sheet 2 Inventor" 1 HE inald Eylnr R. TAYLOR TELEPHONE SYSTEM Dec. 15, 1931.

8 Sheets-Sheet I5 Filed April 13. 1929 Dec. 15, 1931. R TAYLOR TELEPHONE SYSTEM a Sheets- Sheet '4 Filed April 13, 1929 ou e a a Dec. 15, 1931. R. TAYLOR 1,836,996

TELEPHONE SYSTEM Filed April 13. 1929 8 Sheets-Sheet 5 Rs inald T5101" .-4 511 7.

Dec. 15, 1931. R. TAYLOR TELEPHONE SYSTEM Filed April 15, 1929 8 Sheets-Sheet 6 Pm J Dec. 15, R TAYLOR 1,836,996

TELEPHONE SYSTEM Filed April 13. 1929 8 Sheets-Sheet 7 Iwtfi RE inald Elm" Dec. 15, 1931. R. TAYLOR- 1,836;996

TELEPHONE SYSTEM Filed April 15. 1929 8 Sheets-Sheet a L us Isl

Q; IIQUI 1) DC 1m nu UYT Patented Dec. 15, 1931 UNITED STATES PATENT OFFICE AND TELEGRAPH COMPANY, OF CHICAGO,

ILLINOIS, A CORPORATION OF DELAWARE TELEPHONE SYSTEM Application filed April- 13, 1929, Serial No.

The present invention relates to telephone systems and is more particularly concerned with systems including both automatic and manual exchanges, so that special arrangements have to be provided for setting up calls from manual to automatic subscribers. One method which has been employed for this purpose is to make use of key-sending B operators positions from which the automatic switches may be operated to connect with the wanted party. The usual method of working in such cases has been for the calling subscriber to give the number of the wanted subscriber to an A operator in the usual manner and for the A operator then to pass the number to a disengaged B operator over an order wire. Inasmuch as the order wires are common to a large number of operators, this method is not always entirely satisfactory,

.since numbers are apt to be transposed or mutilated, and there is also a danger that the A operator will not properly take up the junction assigned to her by the B operator.-

It is a feature of the present invention to v provide an arrangement in which order wires are eliminated, and in which the wanted number is passed to the key-sending B operator over the junction which will be used for completing the call. By this arrangement there is considerably less danger of the number being passed incorrectly, and there is a further advantage in that it is possible for the B operator to talk to the calling subscriber in case this should be desired.

It is generaly desirable, in the interests of economy, to arrange the senders in a single large group, an idle sender being selected by a hunting switch; in previous arrangements it was possible for an operator to commence i manipulating her keys before an idle sender has been associated. with her position. This trouble is definitely avoided according to a feature of the present invention, by arranging that an impulse sender is first associated with the trunk which is to be used for com- 354,717, and in Great Britain May 2, 1928.

pleting the connection, and an idle operators position is then associated with this impulse sender. With this arrangement the operator can be certain that when a number is passed to her by an A operator an idle impulse sender is already associated with her position.

The arrangement described is intended to be emplo ed at what are known as semi-B operators positions which will be located in an automatic exchange and to which calls intended for that exchange only will be trunked. The invention, however, is equally applicable for use at a switching or tandem exchange for passing calls to other automatic exchanges as is often found convenient owing to the trunking and cabling layout of the network, while a further use is in a satellite area where the B operators could all for instance be located at the main exchange, and forward calls to small automatic exchanges in the vicinity. In the case of a network designed on a 10,000 line exchange basis, it will be necessary to send four digits corresponding to the numerical designation of a wanted party and the sender shown is arranged for the sending of four digits though it will be appreciated that the invention is in no sense limited to this arrangement. The senders themselves are preferably arranged for operation from a single key strip.

The invention will be better understood from the following description of one method of carrying it into efi'ect which should be taken in conjunction with the accompanying drawings. It will be understood, however, that the arrangement shown is given by way of example only, and that various modifications could be made in the circuit details by those skilled in the art without departing from the spirit of the invention.

Referring now to the drawings, Fig. 1 shows an outlet finder OF which is arranged to associate the seized junction relay set JR with one of the four relay groups such as RG to which it has access. Fig. 2 shows the B operators telephone circuit O1 together with the digit keys and the position finder PF; Fig. 3 shows the various controlling relays of the sender and junction finder relay groups; Fig. 4.- shows the sender finder SF and also the junction finder J F; Fig. 5 shows the distributing relays and also various other controlling relays associated with the sender circuit; Fig. 6 shows the junction relay group J R together with sundry disconnect and busy keys associated with various portions of the circuit, which are shown combined in a single key 30; Fig. 7 shows the counting relay group and also the first group of storing relays; Fig. 8 shows the. various switching relays associated with the storing relay groups; Fig. 9 shows a trunking diagram of the principles of operation of the invention, while Fig. 10 shows the three remaining groups of storing relays. These drawings should be arranged with Fig. 2 to the right of Fig. 1, Figs. 3, 5,7 and 9 below Fig. 1 and each other in order and Figs. 4, 6-, 8 and 10 below Fig. 2 and each other in order, in which case the interconnecting conductors will then be found to be in alignment and a complete circuit of the invention is thus obtained.

Considering first Fig. 9, the originating manual exchange is indicated and it will be understood that the junction line J terminates in an A operators position O therein. This junction may be individual to a position or may be common to a group of positions in which case suitable testing arrangements will be provided for indicating to the operator whether the line is idle or already in use by another operator. Alternatively, automatic selecting switches could be employed between the operators positions and the outgoing trunk lines so that the act of inserting a plug would extend a connection to an idle junction line. At the incoming end the junction is connected to a junction relay set J R and on the junction being taken by the A operator a starting impulse is extended by means of the outlet finder OF to a relay group RG which controls the junction finder J F, sender finder SF and position finder PF. These three finders hunt simultaneously to find idle lines in their respective banks, but the operators position O1 is not switched to the connection until all three finders have come to rest. This arrangement of switching ensures that before the B operators position O1 is extended to the junction a sender is always available.

The A. operator who may conveniently be notified of the through connection by means of a tone or lamp signal now passes the call over the junction to the B operator who proceeds to set up the required number on the storing relays in the sender SN by means of her key set. WVhen the complete number is set up, the position is disconnected from the incoming junction and the sender is connected to the selector S. At this point also the outlet finder OF is stepped to connect the common start conductor from the relay set JR to the next relay set. hen the sender SN has completed its functions, it is freed and the selector S is transferred to the junction relay set and thence to the junction and calling party. The junction finder J F, sender finder SF and associated relays are now released aud are available for further use.

It will be appreciated that with this arrangement there is no possibility of interference of the type which is liable to occur with order wire working, and moreover if in some exceptional case the B operator should forget the required number it is still possible for her to connect with the calling subscriber and ask him to repeat it, while previously he would have been required to hang up and start afresh.

A description will now be given of the establishment of a connection between a call ing subscriber in a manual exchange and a wanted subscriber in an automatic exchange, whose number we will assume, for example, to be 12342.

when the calling manual subscriber has initiated a call in the Well known manner, the answering A operator at the manual exchange will then insert one of the calling plugs into a jack associated with a junction line outgoing to the desired automatic exchange, whereupon battery via the cord circuit is applied to the positive line (Fig. 6) and an e-arthedsupervisory relay is connected to the negative line. Hence, a circuit is now closed to relay L from battery over the positive line, relay L operates and prepares a holding loop to the selector S atarmature 10, prepares a locking circuit to relay BG at armature 11 and at armature l2 completes an operating circuit to relay LZ. Upon the operation of the latter relay a circuit is prepared to relay PS at armature 13, and at armature l i a circuit may be traced by way of the resting armatures 15 and 16 to the winding of relay AS to battery. Relay AS thereupon operates over the circuit previously traced and provides a locking circuit for itself via armature 17 to earth at armature 18 of. relay BG, and it will be noticed that the positive and negative lines of the incoming junction from the manual exchange will now be extended by way of armatures 19 and 20 over conductors 82 and 17 5 to the junction finder J F, Fig. t.

The operation of relay AS also causes earth at armature 21 to be disconnected from conductor 22 in order to mark the junction relay set, Fig. 6, idle for access by a junction finder: and earth at the back contact of armature 23 of relay J S is connected via armature 24, conductor 25, armature 26, Fig. 4, conductor 27. wiper 28 and fourth back contact of the outlet finder OF, conductor 29, resting contacts of disconnect and busy key 30, Fig. 6, conductor 3'1, armatures 32 and 33, Fig. 3, winding of relay FSto battery. Upon the operation of relay FS over the circuit just traced, iunting circuits are complcted'simultaneously for the sender finder, unction finder and position finder driving magnets, will now he described. Upon the operation of relay FS, light armature 34 is closed and a circuit may be traced from earth at wiper 35, of sender finder SF (assuming that wiper 35 is resting on a busy contact), conductor 36, armatures 37 and 34, conductor 38. interrupter springs 39 and winding of driving magnet DM2 to battery, thereby causing wipers of the switch to be advanced onto the next set of bank contacts in the well known manner. It will be noticed also that a circuit is prepared to the upper winding of the relay KS at armature 40 of relay F3. from earth over armature 55, conductor 56. and resting contacts of busy key 30. but so long as earth is encountered by test wiper 35 of the sender finder SF, relay KS will be maintained shortcircuited from earth connected to both terminals of its upper winding. Similarly, a circuit may also be traced to the driving magnet DM4 of the junction finder JF, Fig. 4. from earth by way of the busy bank contact and test wiper 41. Fig. 4. conductor 42, resting contacts of key 30. Fig. 6. conductor 43, armaturcs 44 and 45, Fig. 3, conductor 46, interrupter springs 47 and winding of driving magnet DM4, Fig. 4 to battery. Hence. the wipers of the junction finder switch will be advanced to an idle bank contact in the well known manner. It may he mentioned at this point that the operation of the associated switching relay KJ, Fig. 3 will be delayed until relav KR has operated i. e. until the sender finder switch has found an idle sender. The following circuit is'also completed to ma .Q'net DM 3 of the position finder PF, from earth via the bank contact and test wiper 43. Fig. 2. conductor 49, armature 50. conductor 51, armature conductor interrupter springs 54. winding of driving man?- net DM3 to batterv. Consequently. the driving magnet ot the switch will cans the wipers to be advanced to an idle bank contact in the well known manner, and it may be mentioned a this point that the operation of the asociated switching relay KP. Fig. 4- will be delayed until both relav KB and relay KJ ha e operated. i. e. until both the sender finder and the junction finder have switched through. Hence. it will be appreciated that even if the position finder has completed its hunting operation before the cnder and j un 0- tion finders it cannot switch to connect up the B operator until. the sender and junction finders h ve both switched through.

Returning now to the sender finder SF. as soon as a free sender is available the test wiper 35 will no longer encounter earth and the associated switching relay KS will immediately operate from battery via the winding of the driving magnet DM2, Fig. 4, interrupter springs 39, conductor 38, upper winding of relay KS, armatures 40 and 55, conductor 56, resting contacts of key 30, Fig. 6, to earth; upon operating, relay KS com pletes a circuit for its lower locking winding at armature 56 to earth over the initial energizing circuit.

Upon the complete operation of relay KS earth is connected at armature 37 over a circuit previously traced to the test wiper 35 in order to mark the sender finder busy, at armature 57 relay KS opens-a point in a circuit of magnet DMl of the outlet finder OF, Fig. 1, opens a point in another circuit of magnet DMl of the outlet finder OF at armature 58 to prevent continuous rotation when all sender finders are engaged, and at armature 59 extends earth over conductor 6'0 to operaterelay KR. Relay KR operates over the foregoing circuit and at armature 61 opens the operating circuit of relay PY, at armatures 62, 63, 64 and 65 prepares the storing leads, at armatures 66 and 67 prepares the speaking circuit to the B operator, at armature 69 prepares a circuit to relay KP and at armature 68 extends earth by way of conductor 70, winding of relay KJ, conductor 46, interrupter springs 47, winding of driving magnet DM4 of the junction finder JP to battery.

Relay KJ accordingly operates over the foregoing circuit, but, due to the limitation of current in the circuit by the comparatively high resistance of the winding of relay KJ, magnet DM4 is prevented from operating at this time. The operation of relay KJ disconnects the test wiper 41 from the magnet circuit at armature 44, opens a further point in the circuit to magnet DMl of the outlet finder OF 'atarmature 71, prepares a circuit. to relay SY at armature 7 2 for starting the sending operation at the correct instant, at armature 73 prepares a circuit to the time pulse relay TY and also completes the following circuit to operate relay KP when the position finder selects an idle position; earth at-armature 60 of relay KR, Fig. 4, conductor 74. armature 75, conductor 76, winding of relay KP, conductor 53, interrupter springs 54, winding of driving magnet DM3 of the )osition finder PF to battery; here again the magnet is prevented from operating at this time due to the comparatively high resistance of relay KP.

Consequent upon the operation of relay KP the leads from the digit keys, Fig. 2, are extended by way of the banks of the position finder PF, and sender finder SF to the storage relays MlV, MX, MY and MZ shown in Fig. 7 a circuit is prepared at armature 78 to the junction releasekey 77 Fig. 2; relay KP also completes the B operators speaking circuit at armatures 79 and 80, and opens the holding circuit of the start relay FS at armature 26. A still further circuit may also be traced upon the operation of relay KP from earth via a supervisory relay at the distant manual exchange, negative line, Fig. 6, armature 19 of relay AS, armature 81, conductor 82, bank contact and Wiper 83 of the junction finder JF, armatures 66 and 79, conductor 84, wiper 85 and bank contact of position finder PF, conductor 86, winding of relay LO, Fig. 3 to battery. Relay LO accordingly operates over the circuit described, thereby connecting earth to the position meter PM in order to register the call, and also completes the circuit to the position pilot lamp PL, thus indicating to the B operator that the position has been selected by a calling A operator. Similarly, the operation of the supervisory relay and associated signal circuit at the distant manual exchange will indicate to the calling A operator that the B operator is ready to receive her request.

Since the required number has been assumed to be 1234, the B operator after receiving this number from the A operator, will first depress the digit key 1, shown in Fig. 2, thereby causing earth to be extended by way of bank contact and wiper 87 of the position finder PF, conductor 88, armatures 89 and 62, wiper 90 and bank contact, conductor 91, resting contacts of key 30, conductor 92, armatures 93 and 94, Fig. 5, conductor 95, armature 96, Fig. 8, conductor 97, winding of relay MW, Fig. 7, to battery. Relay MW operates over the foregoing circuit, and at armature 98 prepares a circuit to relay SZ, Fig. 5, in order that relay SZ may stop the transmission of the first series of impulses at the correct instant as will be described later; upon the release of the digit key 1 the following holding circuit becomes effective :battery via winding of re lay MW, Fig. 7, armature 99, conductor 100, Winding of relay DM. Fig. 8, conductor 101, armatures 102 and 103, Fig. 5, to earth. Relay DM is operated in series with MYV and at its armatures 96, 104, 105 and 106, transfers the digit set-up leads 95, 113, 257 and 149 to the group of storing relays shown in Fig. 8, comprising relays CW, CX, CY and CZ, thereby preparing the circuit for the reception of the second digit.

Upon the operation of the second digit key 2, the following circuit may be traced to the second group of storing relays, earth by way of back contact and wiper 107 of the position finder PF, conductor 108, armatures 116 and 63, wiper 109 and bank contact of sender finder SF, conductor 110, armatures 111 and 112, conductor 113, armatures 106, and 114, Fig. 8, conductor 115. winding of relay CX to battery. Relay CX accordingly operates over the foregoing circuit and it must be mentioned that a similar group of armatures (not shown) to those located immediately above the M storage group of relays are associated with each of the remaining sets of storage relays groups C, D, and U, Fig. 10, and the conductors extending from these armatures are shown diagrammatically as the common leads 116 in Fig. 7.

Consequent upon the release of the second digit key, Fig. 2, relay CX will lock up over the circuit, battery via the winding of relay CX, armature 117, conductor 118, winding of the associated switching relay DC to earth at resting armature 103. Fig. 5, over a circuit previously traced. The particular combination set up in the second group of storing relays Will result in the sending opera-tion being stopped after the digit 2 has been sent, and upon the operation of relay DC over the circuit traced the digit set-up leads will be transferred on to the third set of storing relays in preparation for the reception of the next digit.

It will therefore be appreciated by those versed in the art that the remaining digits 3 and 4 will be stored in like manner on their associated sets of storing relays, and that upon the reception of the last digit in the train, switching relay DU, Fig. 8, will be 0perated, thereby disconnecting the digit setup leads at armatures 119, 120, 121 and 122 in order to prevent possible mutilation of the last digit stored, in case the operator should inadvertently press a still further digit key. At the front contact of armature 122 a start circuit is prepared to relay SS, Fig. 5, whilst at armature 123 a circuit is also completed to relay SY, Fig. 3, from earth over conductor 124, armature 125, conductor 126, bank contact and wiper 127 of the sender finder SF, conductor 128, armature 72, upper winding of relay SY to battery.

Upon the operation of relay SY over the circuit traced, a 'further point in the energizing circuit of relay FS, Fig. 3, is opened at armature 33, at armature 130 the circuit is prepared to relay PY. and at armature 131 the circuit is completed to relay MB, Fig. 5, as partially set-up calls only, i. e., when relay DU is not operated, in which case the call may be either cleareddown or alternatively routed to an operator depending upon the jumpering of the IDF, shown enclosed by dotted rectangle in Fig. 7. At armature 132 of relay SY earth is again connected to test wiper 35 and bank contact of the sender finder in order to maintain the sender marked busy and at armature the holding circuit to switching relay KS is opened.

Accordingly, relay KS releases and in turn at armature 59 opens the circuit to relay KR, which also releases, thereby entirely disconnecting the B operators position equipment, and at armature 68 and 69 opens the holding circuits to switching relays KJ and KP respectively Hence, upon the release of relay KR the following circuit may be traced to relay PY; earth at armature 133 of relay AS.

Fig. 6, conductor 134, bank contact and wiper 135 of the junction finder JF, armature 61, conductor 136, armature 130, winding of relay PY to battery, thereby causing relay PY to operate and lock up by way of its own operated armature 137 and conductor 138 to earth over the initial energizing circuit.

Upon the complete operation of relay PY the circuit of relay FS is opened at armature 32 and at armature 139 a point is opened in the circuit of magnet DM1 extending over its fifth bank contact, at the same time relay PY completes a circuit for magnet DMl over its fourth bank contact and armature 269 so that the outlet finder is stepped on to the fifth set of bank contacts and then, if all the relay groups are not busy it is stepped to select the next idle relay group. A further guarding earth is connected to the sender finder bank contact at armature 140, and the following circuit is completed to operate relay J S, Fig. 6; earth, armature 141 of relay RR, Fig. 3, armature 142, conductor 43, resting contacts of key 30, conductor 42, wiper 41 and bank contact of junction finder J F, conductor 22, armature 21, Fig. 6, winding of relay J S to battery. Similarly, at the same instant, relay SS. Fig. 5, is operated over the following circuit; earth, armature 143 of relay PY,

Fig. 3, conductor 144, wiper 145 and bank contact of the sender finder SF, conductor 146, armatures 147 and 148, conductor 149, armatures 104, 150, 151 and 122, Fig. 8, conductor 152, winding of relay SS, Fig. 5, to battery.

The operation of relay J S over the circuit previously traced, causes retard coil LA to be disconnected from the negative line at armature 228, opens the start earth at armature 23, provides a locking circuit to relay AS at armature 154, completes anoperating circuit to relay BG at armature 23, and at armatures 81 and 155 causes the sending circuit to be connected to theassociated grou selector circuit over conductors 162 and 176. The following circuit may also be traced: earth, armature 13 of relay LZ, armature 156, winding of relay PS to battery, thereby causing relay PS to operate and lock up to the initial energizing circuit by way of its own operated armature 157 a further locking circuit for relay PS may be traced by way of armature 158 to'earth at the operated arma ture 18 of relay BG. The operation of relay PS prepares at armature 159 a circuit over which retard coil LA will be connected to the negative junction line conductor by the intermittent operation of relay I in case the called party should test busy, connects earth at armature 160 over the test conductor 161 to mark the selector busy, and at armature 229 prepares a holding loop to the selector which is completed when relay J S releases at the conclusion of the sending operation.

Returning now to the operation of relay SS, Fig. 5, a loop circuit to the selector may be traced byway of the negative conductor 162, operated armature 81, conductor 82, bank contact and wiper 83 of the junction finder JF, conductor 163, armature 164, conductor 177, wiper 109 and bank contact of the sender finder SF, conductor 110, armature 165, armature 167 in parallel with the interrupter springs 166, which are pulsing conveniently at the rate of ten per second, armature 168, conductor 169, bank contact and wiper 170 of the sender finder SF, conductor 171, armature 172, conductor 173, wiper 174 and bank contact of junction finder JF, conductor 175, armature 155, to the positive conductor 176; thus causing the selector to be prepared for impulsing.

Earth at armature 178 of relay SS is extendedover conductor 179 for the purpose of effecting the operation of a totalling meter, and at armature 180 an impulsing circuit is completed to the chain of counting relays shown in Fig. 7, consisting or" six relays for counting to a maximum of eleven. Although ten is the maximum number of impulses required per digit, eleven may be counted since the first impulse is absorbed in order to ensure the first impulse actually transmitted may be a complete one. It must be mentioned at this point that the two sets of impulsing springs 166 and 181, Fig. 5, are arranged to be out of phase with each other so that when one set of springs make contact the other set will then break contact. Referring now particularly to the sending of the first digit which it will be recalled is one, and assuming that impulsing springs 181 have now made contact, then a circuit may be traced from earth via impulsing springs 181, armatures 182 and 180, conductor armatures 184, 185, 186, 187 and 188, upper winding of relay SA to battery, thereby causmg the relay to operate its light armature p 189 and at the conclusion of the impulse the relay will then fully operate over both windlngs in series, via armatures 189 and 190, conductor 191, armatures 192 and 102, to earth at the resting contact of armature 103 of relay CO, Fig. 5. Upon. the complete operation of relay SA the impulsing circuit will be transferred at armature 188 to the second counting relay SC, and at armature 193 earth will be extended over conductor 194 to operate relay SB; but it will be appreciated that although the short-circuit across the impulse. springs 166 is opened by the operation of armature 167 the loop circuit to the selector will be maintained by way of the impulse springs 166 which are made at this instant. Consequently, upon the next earth impulse by way of impulsing springs 181, the second counting relay SC will then be operated to its light armature 195, and as the impulse springs 166 will open at this instant,

an impulse will be transmitted to the group selector over the loop circuit previously traced. At the conclusion of the earth impulse via impulse springs 181, relay SC will operate fully over both windings in series in a similar manner to that described for relay SA.

Hence, upon the full operation of relay SC and remembering also that relay MW of the first storing group is also operated, the following circuit is now completed to the second stop relay SZ; earth at armature 196 of relay CM, Fig. 5, armature 197, conductor 198, armatures 98, 199, 200 and 201, arma tures 202 and 203, conductor 204, winding of the stop relay SZ to battery. Relay SZ thereupon operates and the impulse springs are immediately short-circuited at armature 205 to prevent any further impulses being sent to the group selector. The locking circuit to the counting relays is opened at armature 192, the impulsing circuit to the counting relays is opened until the correct instant at armature 182, and relay SZ locks operated by way of armatures 206 and 207 and remains operated until relay SB releases. It will be appreciated that as both relays SZ and SB are slow to release due to the copper slugs surrounding their cores, the combined slow periods of these relays will produce the necessary pause between the various digits.

It will also have been noticed that upon the operation of relay SB the following circuit is completed, earth at armature 103 of relay CO, Fig. 5, armature 102, armatures 208 and 209, lower winding of relay GM to battery, and in consequence thereof relay CM operates its light armature 210, so that when relay SB releases at the termination of the first digit, relay GM will then operate fully over both windings in series to earth over the initial energizing circuit. Upon the full operaton of relay CM the marking earth is then transferred to the hundreds group oi storage relays by way of armatures 196, 211 and 212, over conductor 213, to a similar group of armatures to that located immediately above the thousands storage group and also connected in multiple thereto by means of the common conductors 116 shown in the lower half of Fig. 7. WVhen relay SZ releases after a short interval, the locking earth will again be connecting to the counting relays, and the impulsing circuit will be completed at armature 182.

The previously described sequence of operations will now be repeated, and in this particular instance the counting relay set will operate until relay SD has operated in order to send two impulses before the sending is stopped by the operation of relay SZ as previously explained. It will be noticed also that upon the second operation of relay SB after relay SA has operated completely a circuit is closed for the lower winding of relay "CG, and upon the full operation of the latter relay when relay SB releases the marking earth wi ll be extended to the ten series of storage relays, whereupon, subsequent to the release of relay SZ, the third series of impulses will then commence.

Hence, the above sequence of operations will beagain repeated until the counting relay SE has been operated after an output of three impulses, whereupon relay SB will release and upon the full operation of relay CD the marking earth will then be distributed to the units series of storage relays, and here again subsequent to the release of the stop relay SZ the fourth and last series of impulses will be commenced.

In this case the counting relay set will operate until relay SF has operated after four impulses have been transmitted whereupon the stop relay SZ will again be operated in a similar manner to that already explained.

Upon the operation of relay SZ at the end of the units di it, the following circuit is completed zeal-ti, armature 103 of relay GO, Fig. 5, armature 102, armature 208 of relay SB, armatures 209, 214, 215, 216 and 217, lower winding of relay CO to battery, there by causing relay .CO to first operate its light armature 218 in order to lock up over its other winding in the following circuits: earth, winding of relay RR, Fig. 3, armature 219, conductor 220, wiper 90 and bank contact of sender finder SF, conductor 91, armature 218, Fig. 5, upon winding of relay CO to battery. Upon the full operation of relay G0 a further locking circuit is completed for itself at armature 216, the digit set-up leads to the storage relay groups are disconnected at armatures 93, 111, 221 and 147, the holding loop is maintained by way of armatures 221 and 111, interrupted earth is extended over conductor 222, armature 2241 to the supervisory lamp 223 to indicate a releasing condition, and at armature 225 earth is connected to conductor 226 in order to set in operation the common exchange slow release alarm.

It will be appreciated that the locking circuit for relay CO is controlled via the operated armature 217 of relay SZ in order to ensure the retention of the former relay until the last relay of the sender, i. e., relay SZ, releases.

It will also be noticed upon the operation of relay CO that the shunting earth across the winding of relay RG is removed at armature 103 upon the operation of relay CO, and in case any of the storing, distributing or counting relays should stick or be otherwise retained in an operated condition after the removal of the holding earth at armature 103, high resistance relay RG will then be operated and at its armature 227 maintains relay CO operated in order to guard the sender at the front contact of armature 103 until such time as the fault is cleared.

Returning now to relay RR, Fig. 3, which operates in series with the upper winding of relay CO, it will be seen that at armature 141 the holding circuit to both relavs AS and J S, Fig. 6 will be opened and in consequence these relays will release. Upon the release of relay AS, earth is again connected to the contact of the junction finder J F at armature 21, in order to mark the junction relay set, Fig. 6, busy to other hunting switches; the holding circuit to relay PY, Fig. 3, is opened at armature 133 and this relay releases. Considering now the release of relay J S, the

holding circuit for the automatic train of switches is now transferred to the junction relay set at armatures 81 and 155, at armature 226 the circuit is prepared to retard coil LA for supervision to the A operator, the preliminary operating circuit to relay BG is opened at armature 23, and at armature 156 opens the initial energizing circuit to relay PS is opened. When relay PY releases, the series circuit between relay RR and one winding of relay CO is opened at armature 219 and as a resultrelays RR and CO will then release and the sender circuit will then be accordingly available for further use.

It must be mentioned that when relay J S released, the holding loop to the automatic train of switches was transferred to the following circuit: negative conductor 162, Fig. 6, resting contacts associated with armature 81, winding of polarized relay D, armature 10, winding of high impedance relay I, armature 229, resting contacts associated with armature 155, to the positive conductor 176. Relay I operates over the circuit described, thereby providing an additional holding circuit to relay BG'at armature 230, and at armature 231 prevents the connection of relay LA to the negative line until the correct instant.

Assuming now that the called line tests busy, the well known busy flash arrangements will then be applied to the calling junction at either the group selector or the fixed selector, depending of course on the particular type of busy condition encountered, and in consequence thereof relay I, Fig. 6, will release in synchronism with the flash periods, and accordingly complete a circuit at armature 231 for retard coil LA to the negative line for busy flash supervision to the A operator. Consequently, when the distant A operator observes the cord circuit supervisory lamp flashing, she will then remove the calling plug from the jack, thereby disconnecting battery from the positive line so that relay L in the junction relay group Fig. 6, will then release. Upon the release of relay L the loop via relays I and D to the automatic train of switches is then opened at armature 10,

" and similarly also the circuit to relay LZ is opened at armature 12. The holding circuit of relay BG willalso be opened at armature 230 by the release of relay I, so that both relays LZ and BG will restore almost simultaneously in order to disconnect the locking circuit to relay PS. Relay PS accordingly releases after its slow period has elapsed, and at its armature 160 removes the guarding earth from conductor 161 in order to free the connection.

In case the distant A operator should clear during the flash period, i. e. with relay I normal; upon the release of relay L as previously explained, flash battery extended over the positive conductor 176 will complete an operating circuit to relay I via resting contacts associated with armatures 155, armature 229, winding of relay I, armature 10, armature 232 to earth, and upon the re-operation of relay I, relay BG will be held operated by Way of armature 230 until the conclusion of the flash period. whereupon the subsequent release of relays BG and PS takes place as previously described.

Assuming now that the call is successful, battery will be reversed around the calling loop by the last switch in the train when the called party replies, and as a result the polarized relay D will then be operated, thereby at armature 233 connecting battery via relay LA on to the negative line to provide the necessary supervision at the distant manual exchange to the effect that the called party has answered.

Consideration must now be given to a partial set-up call, wherein the full complement of digits are not set up by the B operator. Earth pulses at conveniently nine seconds duration on and oil are connected over conductor 234to armature 235 of relay TY, Fig. 3, and from thence by way of armature 73 to the lower winding of the time pulse relay TY to battery, thereby causing relay TY to operate its light armature 237, and at the conclusion of the pulse the relay will then fully operate over both windings in series and lock up to earth at armature 238 of relay KJ Consequently, if the operator fails to set up the full complement of digits, relay TY will be held operated via armature 73 of re lay KJ, and upon the reception of the next earth pulse by way of conductor 234, relay SY will be fully operated over its lower winding.

Relay SY, in addition to fulfilling the functions previously explained for a completely stored cell, also extends earth over the following circuit to operate relay MB, Fig. 5; earth, armature 131, conductor 128, wiper 127 and bank contact of sender finder, conductor 126, armature 125, conductor 124, armature 123, conductor 239, winding of relay MB, Fig. 5 to battery. Upon the operation of relay MB over the circuit traced, a locking circuit is provided for itself at armature 240, the digit set-up leads are opened at armatures 94, 148, 241 and 112, at armatures 197, 212, 244 and 243 points are closed in the paths of the marking earth rented by the distributing relays CM, CC and CD .and connected to the associated terminals of the I. D. F. Fig. 7, munbercd 246, 247, 248 and 249. Also at armature 148 a circuit is closed to terminal 245 of the I. D. F.

If partial set-up calls are required to be routed to an operator, I. D. F. terminal 245 is connected to terminal 250, and terminals 24", and 249 are connected to the corresponding sender stop leads in the correct sequence, depending upon the number of digits in the operators number. Hence, when relay KR, Fig. 4, releases, consequent upon the operation of relay SY and the release of relay KS, as previously explained, relay PY will operate in order to complete the following circuit: earth, armature 143 of relay PY, Fig. 3, conductor 144, wiper 145 and bank contact of the sender finder SF, conductor 146, armature 147, operated contacts of armature 148, IDF terminal 245 junipored to terminal 250, conductor 152. winding of the start relay SS, 5 to battery. Upon the operation of relay SS over the circuit described, the counting relays are set in operation, thereby transmitting the digits of the operators number in accordance with the predetermined setting at the IDF terminals.

If the sender is arranged to clear down on all partial set-up calls, the IDF terminal 245 will be connected to terminal 251, so that consequent upon theoperation of relay PY, earth will then be extended over conductor to the lower winding of relay CO, Fig. 5. Relay CO accordingly operates over the foregoing circuit and causes the sender equipment to be restored to normal in the manner already described, while the calling loop is switched through to the first selector at the resting contacts of relay J S.

A description will now be given of the cancel feature. l' s hen it becomes necessary to cancel a set-up in which an error has been made after the first, second or third digit has been stored, the operator will depress the cancel key 253, Fig. 2, whereupon earth will be extended over the following circuit: bank contact and wiper 254 of the position finder PF, conductor 255, armatures 256 and 64, wiper 170 and bank contact of the sender finder, conductor 169, armatures 221 and 241, conductor 257, armature 105, Fig. 8, conductor 258, winding of the storage relay MY or alternatively relay CY or relay DY (after the second and third digits respectively) to battery. A further circuit may be traced from earth via the contacts of the cancel key 253, bank contact and wiper 87 of the position finder PF, conductor 88, armatures 8.9 and 62, wiper 90and bank contact of the sender finder SF, conductor 91, resting contacts of key 30, conductor 92., armatures 93 and 94, conductor 95, armature 96, Fig. 8, conductor 97, winding of the storing relay Ml V or alternatively relay Cl/V or relay DW (after the second and third digits respectively) to battery. Hence, both relays will then be operated to their light armatures over the circuits traced, and upon the release of the cancel key the relays MY and MlV will then fully operate and complete the following circuit: earth, armature 196 of relay CM, armature 197, conductor 198, armatures 98, 199 and 200, conductor 252, lower winding of relay GO to battery. Relay CO thereupon operates .and the sender equipment will then be restored to normal in readiness for the next set-up.

In case for any reason a fault should occur on the junction line, such as to cause the relay L to be operated, it will be readily obvious that the B operator will then be signalled in the usual manner. Such emergency is provided for by the junction release key 77, Fig. 2, whereby upon the depression of said key after the B operator has challenged the junction, earth potential will then be extended by way of bank contact and wiper 259 of the position finder PF, conductor 260, armatures 78 and 261, conductor 128, armature 7 2, upper winding of relay SY, Fig. 3, to battery. Hence, upon the operation of relay SY the faulty connection may then be extended to an enquiry operators position in similar manner to that already described for a partial set-up call. Alternatively, however, the sender may be arranged to clear down under these conditions, in which case the depression of the junction release key will cause the loop to be extended to the first selector, where the fault will be dealt with in due course by the exchange attendant.

It will have been noticed from the drawings that relay SB1, Fig. 3, is controlled by way of battery through its winding, conductor 262, armature 263 of relay CH, in parallel with the operated contacts of the disconnect and busy key 30, Fig. 6, and from thence by way of conductor 264 and similar chain contacts of other senders in the same group to earth, so that when all the senders in that roup are engaged the chain circuit to relay SE1 will then be completed, thus causing the relay to operate. Upon the operation of relay S131, the four fifth bank contacts of outlet finder w ll be opened at armatures 265, 266, 267 and 268, and consequently the circuit of magnet DMl will be held open on any of these contacts so that the switch will be prevented from continuously rotating during an all outlets busy condition.

hat I claim is 1. In a telephone system, a trunk line, an

impulse sender, an operators position, a link circuit including a plurality of hunting switches, and means responsive to the seizure of said trunk line at its distant end for causmg said link circuit to connectsaid operators position, said impulse sender and said trunk line over said hunting switches.

2. In a telephone system, a trunk line, a group of hunting switches, an impulse sender, an idle set of keys, and means responsive to the seizure of said trunk line at its distant end for causing said group of hunting switches to hunt simultaneously to 'associate said trunk line with said impulse sender and said idle set of keys. V

3. In a telephone system comprising of a manual and automatic exchange, an operators position at said automatic exchange, an idle impulse sender, a key set at said operators position for controlling the operation of said impulse sender to complete manualto-automatic calls, a trunk line for connecting said exchanges,an idle link circuit, a

group of hunting switches, and means responsive to the seizure of said trunk line at said manual exchange for associating said operators position, said impulse sender and said trunk line with said link circuit over said group of hunting switches.

i. In a telephone system, a trunk line, an idle link circuit, a backwardly hunting switch, an idle operators position, an idle impulse sender, a group of forwardly hunting switches, and means responsive to the seizure of said trunk line at its distantend for associating said trunk line with said idle link circuit over said backwardly hunting switch and for associating said idle operators position and said idle impulse sender with said idle link circuit over said forwardly hunting switches. 5

5. In a telephone system, an A operators position, a trunk line from said A operators position, an idle link circuit, a group of hunting switches, means responsive to the seizure of said trunk line by said A operator for associating the incoming end of said trunk line with said idle link circuit over one of said hunting switches, an idle impulse said trunk line with said impulse sender and said idle set of keys, and means for preventing said idle set of keys from being associated with said trunk line until all of said hunting switches have stopped hunting.

7. In a telephone system, a junction line,

a plurality of groups of hunting switches, a further hunting switch, means for preselecting one of said groups of hunting switches from said junction line over said further which the operator at the automatic exchange verbally receives the called number from said manual exchange, an idle link circuit, an idle impulse sender, a group of hunting switches, and means responsive to the seizure of said trunk line by said manual exchange for associating said operators position, said impulse sender and said trunk line with said link over said group of hunting switches.

9. In a telephone system, a manual exchange, an automatic exchange, an idle operators position at said automatic exchange, a trunk line connecting said exchanges over which the operator at the automatic exchange verbally receives the called number from said manual exchange, an idle link circuit, an idle impulse sender, a group of hunting switches, means responsive to the seizure of said trunk line by said manual exchange for associating said operators position, said impulse sender and said trunk line with said link circuit over said group of hunting switches, a supervisory signal at said manual exchange, and means responsive to said operators position being associated with said link circuit for operating said supervisory signal to notify said manual exchange that said operators position has been seized.

10. In a telephone system, a trunk line from an A operators position, a sending mechanism, a set of number keys, a signal individual to said keys, means responsive to said trunk line being seized by said A operator for connecting said sender to said trunk line and to said key set, and means responsive only to the completion of both operations for operating said signal.

11. In a telephone system, a register sender, a key set for setting said register sender,

a first relay operated when the last digit of a number is registered, a second relay operated by said first relay to cause the register to transmit the registered digits, a third relay for controlling the operation of said second relay if the first relay is not operated within a predetermined interval, and means operative responsive to the operation of said seconc relay, under control of said third relay, for causing the register sender to restore to normal.

12. In a telephone system, a register sender, a key set for setting said register sender,

a first relay operated When the last digit of a number is registered, a second relay operated by said first relay to cause the register to transmit the registered digits, a third relay for controlling the operation of said second relay if the first relay is not operated Within a predetermined interval, and means operative responsive to the operation of said second relay,=under control of said third relay, for causing the register sender to transmit a predetermined series of digits to route the call to a special operator.

In testimony whereof I have signed my name at Liverpool this 25th day of March,

REGINALD TAYLOR: 

